At present, the charging current is increasing with the development of charging technology, and common-mode interferences result from a connected charger can seriously affect the performance of a touch screen. Currently, most of the touch screen manufacturers have adopted a frequency adaptive algorithm; among which, by detecting the interference frequency of the common-mode interference, a frequency band away from the interference frequency can be selected as a working frequency. However, the charging current is large when a quick charger is connected, and the frequency adaptive algorithm cannot solve the interference caused by the quick charger; even when a normal charger is connected, the frequency adaptive algorithm cannot solve the interference completely.